Pump arrangements of this kind are widely known, particularly as oil pumps for motor vehicle transmissions. In particular, pump arrangements of this kind are known as gear pumps with internal toothing, and these can be designed with or without a crescent. In particular, the present invention relates to gear pumps with internal toothing without a crescent, which are also known as annular gear pumps or gerotor pumps.
Document DE 10 2009 026 148 A1 discloses a gear pump for fuel in which an outer pump member is produced from a plastic or from a sintered steel, wherein magnets or holes are embedded in the material. The pump member thus forms the rotor of an electric motor, the stator of which carries on its inner circumference a sliding bearing produced from a non-ferromagnetic material, such as bronze.
Document WO 2011/012364 A2 furthermore discloses a gear pump for fuel in which a magnet ring is fixed on the outer circumference of an outer pump member. The sliding bearing arrangement of this pump member is set up to achieve a thin annular gap between this pump member and a bearing ring connected to the housing.
The practice of fixing a bearing bush that forms a sliding bearing arrangement for a rotor on the inner circumference of a stator of a gear pump for fuel is furthermore known (DE 10 2010 029 336 A1).
Document WO 2008/017543 A1 furthermore discloses another internal gear pump for fuel, in which a magnet ring is connected to a toothed ring, wherein the magnet ring is accommodated rotatably in the stator in the manner of a sliding bearing. Here, it is supposed to be advantageous to coat the magnet ring in order to achieve a tribologically advantageous pairing of materials.
The publication EP 1 674 728 A2 discloses a pump arrangement in which a stator is arranged outside the actual pump housing.
In the above pump arrangements, the stator is in each case accommodated in a housing. U.S. Pat. No. 2,761,078 discloses the practice of not covering the stator plates at the outer circumference so as to allow better dissipation of heat developed in the stator to the outside. This document furthermore discloses the practice of filling the cavities between the stator poles of the stator with a plastic, thus ensuring that the inner circumference of the stator is closed between the pole shoes. Here, the plastic is to be selected so that it has a better thermal conductivity than air. The rotor of this pump arrangement is supported on the housing by means of bearings.